1. Field of the Invention
The present invention relates to a motion vector detecting device, a motion vector detecting method, an image encoding device, and a program capable of reducing an amount of operations accompanied with a detection of a motion vector.
2. Description of Related Art
Techniques of efficiently transmitting and storing image data effectively using the redundancy of the image data in transmitting and storing moving images associated with broadcast stations were developed in the past. In such techniques, the image data is compressed by orthogonal transformation such as discrete cosine transformation and motion compensation on the basis of standards such as MPEG (Moving Picture Experts Group).
MPEG2 (ISO/IEC 13818-2) as an example thereof is a standard defined as a general-purpose image encoding standard. It is defined to cope with both interlaced scanning and progressive scanning and to cope with both a standard-resolution image and a high-precision image. The MPEG2 is widely employed by wide-ranged applications for professionals and consumers. In accordance with the MPEG2, it is possible to secure a high compression rate with high quality.
However, the MPEG2 is a high-quality encoding standard suitable for broadcast and does not cope with high-compression-rate encoding having an encoding quantity smaller than that of the MPEG1. Therefore, in consideration of needs for the high-compression-rate encoding having an encoding quantity smaller than that of the MPEG1, an encoding scheme is standardized on the basis of MPEG4 (ISO/IEC 14496-2).
H26L (ITU-T Q6/16 VCEG) designed to encode images for TV conferences has been standardized and the encoding scheme of taking in various functions based the H26L to secure higher encoding efficiency has been standardized as Joint Model of Enhanced-Compression Video Coding by an action of the MPEG4, which were established as H.264 and MPEG4 Part 10 (AVC: Advanced Video Coding).
A motion compensation of dividing an image frame into blocks and predicting a motion from an encoded frame has been employed in the image encoding scheme based on the H.264/AVC.
As such a type of technique, for example, in JP-A-2004-241957, simple SATDs (Sum of Absolute Transformed Differences) are calculated from differences between pixel data in a motion compensating block of the present frame and pixel data in a motion compensating block of a reference frame in detecting a motion vector and a motion predicting and compensating circuit specifies the motion vector having the minimum estimated value defined using the simple SATDs.